Dispaly Temperature from MAX6675 using ESP32 over Bluetooth on Mobile phone

In this tutorial we learn how to use MAX6675 Thermocouple sensor with ESP32 to measure temperature and read it using Bluetooth on mobile phone or tablet devices.
If you need to use MAX6675 thermocouple sensor with ESP32 (no bluetooth) See this page
If you need to use 2 or more MAX6675 thermocouple sensor with ESP32 (no bluetooth) See this page

The link to use in the "preferences" of Arduino IDE for ESP32 board https://dl.espressif.com/dl/package_esp32_index.json Watch video for instructions.

Arduino code for MAX6675 with ESP32 Bluetooth


 /*
 * 
 * 
 * This is Arduino code to Measure Temperature over Bluetooth using
 MAX6675 with ESP32 to display on Tablet or mobile device
 
 * Watch video instruction for this code:  https://youtu.be/Zm8Xor_vYF4
   
 * Written/updated by Ahmad Shamshiri for Robojax Video channel www.Robojax.com
 * Date: July 08, 2020, in Ajax, Ontario, Canada

Related videos:
Introduction to MAX6675 K-Type: https://youtu.be/VGqONmUinqA
Using MAX6675 K-Type thermocouple whit LED display: https://youtu.be/cD5oOu4N_AE
Using MAX6675 K-Type thermocouplewith LCD1602-I2C: https://youtu.be/BlhpktgPdKs
Using 2 or more MAX6675 K-Type thermocouple: https://youtu.be/c90NszbNG8c
Using MAX6675 K-Type with ESP32 over Bluetooth: [this video]
 
 * this code has been downloaded from http://robojax.com/learn/arduino/
 
 * Get this code and other Arduino codes from Robojax.com
Learn Arduino step by step in structured course with all material, wiring diagram and library
all in once place. Purchase My course on Udemy.com http://robojax.com/L/?id=62

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 *  * This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.* 
 * This code has been download from Robojax.com
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

///////// Start of MAX6675 settings

#include "max6675.h"
//Robojax.com  MAX6675 Thermocoupler

int thermoCLK = 12;
int thermoCS = 14;
int thermoDO = 27;
float tempC, tempF, tempK;
char *titleTemp="Temperature: ";
int type=1;// 1=C, 2=F, 3=K,
MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
/////////////// end of MAX6675 settings


#include "BluetoothSerial.h"
#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run `make menuconfig` to and enable it
#endif

BluetoothSerial SerialBT;
int inData;

char receivedChar;// received value will be stored as CHAR in this variable

void setup() {
  Serial.begin(115200);
  SerialBT.begin("ESP32_Robojax"); //Bluetooth device name
  Serial.println("The device started, now you can pair it with bluetooth!");
  Serial.println("Search for ESP32_Robojax device and Pair your phone to ESP32_Robojax");  
  
 
	  //Robojax.com MAX6675 with ESP32 Bluetooth

}

void loop() {
   getTemp();
 Serial.println(thermocouple.readCelsius());
  //Robojax.com MAX6675 with ESP32 Bluetooth
  if (Serial.available()) {
   // SerialBT.write(Serial.read());
  
  }
  while (SerialBT.available() ) {
    receivedChar =(char)SerialBT.read();
    inData += receivedChar;    
        if (receivedChar == '
')
        {    
   //SerialBT.print("Received:");// write on BT app
   //SerialBT.println(inData);// write on BT app   

   //Serial.print("Received:");//print on Serial Monitor
  // Serial.println(inData); //print on Serial Monitor     
    
    type = inData;
    sendTemp();
   
           inData = 0; // Clear recieved buffer                    
                  
        }//if (receivedChar


  }// while


        delay(300);
//Robojax.com MAX6675 with ESP32 Bluetooth
}//loop ends here

void sendTemp()
{

//Robojax.com MAX6675 with ESP32 Bluetooth
      SerialBT.print(titleTemp);
    if(type ==24)
    {
      SerialBT.print(tempC);
      SerialBT.println("°C");

    }
    if(type ==25)
    {
      SerialBT.print(tempF);
      SerialBT.println("°F");

    }
    if(type ==26)
    {

      SerialBT.print(tempK); 
      SerialBT.println("°K");

    } 
//Robojax.com MAX6675 with ESP32 Bluetooth	
}//sendTemp ends here



/*
 * @brief returns temperature or relative humidity

 * @return returns one of the values above
 * Usage: to get Fahrenheit type: getTemp('F')
 * to print it on serial monitor Serial.println(getTemp('F'));
 * Written by Ahmad Shamshiri on Mar 30, 2020. 
 * in Ajax, Ontario, Canada
 * www.Robojax.com 
 */
void getTemp()
{
 //Robojax.com with MAX6675 Thermocoupler 

   tempF = thermocouple.readFahrenheit();// Fahrenheit 
   tempK= thermocouple.readCelsius() + 273.15;//convert to Kelvin
   tempC = thermocouple.readCelsius();// Celsius
  
 //Robojax.com  MAX6675 Thermocoupler 
}//getTemp